The present invention relates generally to stretch releasing adhesive tapes for removably adhesively bonding an object to a surface. More particularly, the present invention relates to a single or double-sided stretch releasing adhesive tape article that can be made in an elongated strip of indefinite length which can be cut to a selected length depending on the end use application for the tape, and a pull tab for stretch removing the tape can be formed at any location along the tape using a segmented liner.
Stretch releasing adhesive tapes represent an emerging class of high performance pressure-sensitive adhesives combining strong holding power with clean removal and no surface damage. Such stretch releasing adhesive tapes are useful in a wide variety of assembling, joining, attaching, and mounting applications.
Adhesive tape strips which can be cleanly removed from a surface by stretching the tape strip are known in the patented prior art. The Korpman U.S. Pat. No. 4,024,312, for example, discloses a highly conformable adhesive tape including a highly extensible and elastic backing film laminated with an adhesive layer. The backing film possesses a lengthwise elongation at break of at least about 200%. The tape is easily stretchable and may be removed from a surface by stretching the tape lengthwise in a direction substantially parallel to the surface. German Patent No. 33 31 016 discloses a high elasticity, low plasticity adhesive film based on a thermoplastic rubber and tackifying resins, wherein the adhesive bond can be broken by stretching the adhesive film in the direction of the plane of the adhesive bond.
The Kreckel et al. U.S. Pat. No. 5,516,581, assigned to the same assignee as the present invention, discloses a removable adhesive tape having a highly extensible and substantially inelastic backing coated with a layer of pressure sensitive adhesive. The adhesive tape can be removed from a substrate without damaging the substrate by stretching the tape in a direction substantially parallel to the surface of the substrate. The tape backing has a lengthwise elongation at break of from about 150% to about 1200%, a Young""s modulus of at least about 2,500 psi to about 72,500 psi, and an elastic recovery of less than about 50% after being stretched and removed. PCT International Publication No. WO 95/06691 discloses removable foam adhesive tape comprising a backing including a layer of polymeric foam, and a layer of pressure-sensitive adhesive coated on at least one surface of the backing. The foam layer of the backing has a thickness of about 30 to about 1000 mils, and the backing has a lengthwise elongation at break of from about 50% to about 1200%, and a Young""s modulus of less than about 2,400 psi.
Commercial stretch releasing adhesive tapes include the product sold under the trade designation COMMAND by Minnesota Mining and Manufacturing Company, St. Paul, Minn., and the product sold under the trade designation POWER-STRIPS by Beiersdorf A G, Hamburg, Germany. These products are currently manufactured as discrete strips with one end of the strip including a non-adhesive pull tab to facilitate stretching of the strip during removal. The adhesive surfaces of the strip are additionally protected with a release liner.
Desirable for certain applications is a strip having a discrete length from which multiple strips of various length can be cut, or an elongated strip of indefinite length or roll of stretch releasing adhesive tape from which strips of variable length can be cut depending on the end use application. The difficulty with providing a long length of stretch releasing tape which can be cut to a selected length is the ability to provide a non-adhesive pull tab at a specific location on the cut strip, usually at the end of the cut strip, to serve as a grasping area for stretching the strip from a substrate at the time of removal.
PCT International Publication No. WO 98/06652 discloses a length cutting fixture which can be used to form a non-adhesive pull tab or xe2x80x9cgripperxe2x80x9d at the end of a long length of a conventional single-sided adhesive tape. The length cutting fixture also serves to cut the long length of tape, now including the gripper, to any desired length. The gripper is formed by folding the end of the tape back onto itself. Such a length cutting fixture, however, cannot be used to form a non-adhesive pull tab on a double-sided adhesive tape.
It is therefore desirable to provide a stretch releasing adhesive tape article in a long length which can be cut into discrete strips having any selected length, wherein each strip can be provided with a non-adhesive pull tab at a specific location to serve as a stretch removal tab which can be grasped and pulled by a user to remove the adhesive tape from a substrate.
The present invention provides a stretch releasing adhesive tape article including an elongate length of stretch releasing adhesive tape and a segmented liner arranged on the adhesive that can be used to form a manually engageable pull tab at a selected location on a discrete strip of tape cut from the long length of tape. The adhesive tape article can be a flat strip or can be wound upon itself to form a roll. The segmented liner allows the adhesive tape to be made in a long length which can be wound into a roll, allows a user to cut a discrete strip from the long length depending on the end use application for the strip, and allows the user to form a non-adhesive pull tab at any location on the strip which can be grasped and pulled by the user to stretch remove the tape from an associated substrate. For easy access, the pull tab is preferably formed adjacent an end of the adhesive strip.
More particularly, the stretch releasing adhesive tape article includes an elongate length of stretch releasing tape having first and second oppositely facing major surfaces and first and second ends with at least one of the first and second major surfaces being adhesive, and at least a first segmented liner arranged on an adhesive surface. A preferred stretch releasing adhesive tape is available under the COMMAND trade designation from Minnesota Mining and Manufacturing Company, St. Paul, Minn. The liner can be a silicon coated paper.
In one embodiment, the segmented liner is formed from separate, individually removable, aligned segments arranged along the adhesive surface or surfaces of the adhesive tape. In another embodiment, the segmented liner is a single liner including at least one frangible connection dividing the liner into segments that can be readily separated. The frangible connection can be formed by cutting slits into the liner, thereby leaving a connecting portion between adjacent segments that can be easily broken, by punching holes in the liner to form perforations, or by other known techniques. In addition, the frangible connection can be formed without creating a physical discontinuity in the liner by providing a line of weakness in the liner by, for example, scoring, notching, or creasing the liner, thereby allowing a user to easily tear the liner along the line of weakness.
By forming the segmented liner from a plurality of individual liners each of which define a segment, or from a single liner including one or more frangible connections or lines of weakness which define individual segments, selected liner segments can be separated from the rest and left on the adhesive tape to form the pull tab while the remaining liner segments can be removed from the tape to expose an associated adhesive surface. For the embodiment where the segmented liner is formed with frangible connections or lines of weakness thereby forming a liner with a series of interconnected segments, a series of connected liner segments to be removed from the adhesive tape can be removed simultaneously.
If both the first and second major surfaces are adhesive, segmented liners can be provided on both surfaces. Alternatively, one release liner having a width approximately twice that of the tape can be used. Such a liner allows the tape to be wound into a roll without bonding to itself and further allows the liner to be folded onto the opposite major surface to form a pull tab. The liner can include a longitudinally extending lower adhesion surface portion normally in contact with the tape adhesive surface, and a higher adhesion surface portion normally extending beyond the tape which can be folded back onto the tape and form a strong adhesive bond therewith to form a pull tab that will not readily debond from the adhesive tape. The liner surface opposite the surface with the lower and higher adhesion surface portions can include a releasable surface portion and a high friction surface portion with a rubber-like or textured surface to aid in gripping the liner portion which has been formed into the pull tab.
In a specific embodiment, the liner includes transversely extending wing portions and a longitudinally extending connecting portion forming the frangible connection between adjacent wing portions. In another embodiment, the longitudinally extending connecting portion defines a center portion of the liner, whereby pairs of aligned wing portions extend outwardly in opposite directions from the connecting center portion which can be folded back onto the tape to form the pull tab.